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Amplifier design parameters required for a good match for high (16+) ohm speakers?

Though I have a reasonable understanding of, or at least am satisfied with, the requirements for an amplifier asked to drive low impedance speakers, I am wondering about specific design parameters that might need be considered when mating an amplifier to high impedance ones. Asked another way: Are there specs that one should seek out when searching for an amplifier to be mated to such speakers?
mesch
atmasphere's avatar
atmasphere
11,590 posts
 
Ralph said it was in the best condition of amy he has seen for that time. It was factory manufactured, not put together as a kit. I own a original owners/instruction manual for the kit version so following it, I could likely replace the power supply caps myself if I feel the need.
If it came though here, then we replaced the filter caps. The ones installed allow the 5AR4 to be used, but do have a bit more capacity than stock. We also replaced the bias supply filter caps and rectifiers and probably the coupling capacitors too- the amp was set up to be reliable.
atmasphere's avatar
atmasphere
11,590 posts
 
Ralph, I am using the 16ohm output with the Contrasts, which are rated at 16ohms. I am not sure about actual impedance within the bass frequencies.
Which model?
mesch OP
3,401 posts
 
Ralph, I haven't put many hours on my ST-70 since I had you refurbish it in spring of 2016. However I now fell in position to do so. Took a long time for me to find a complimentary set of  speakers I could afford.  I have never any doubt that my ST-70 would prove reliable. As an aside, how do the St-70s fair when used in mono mode? 

Speakers are Contrast Model One AS3 Ref. 
atmasphere's avatar
atmasphere
11,590 posts
 
The Model One should be very nice with the ST-70. They rate the sensitivity at 92 dB if memory serves; if that is actually sensitivity, the speaker is 95dB 1 watt/1 meter, which will mean the ST-70 has adequate power. If the amp has not been used much, it will need some break-in time during which is will become more lucid.

By mono mode, do you mean monostrapped?
mesch OP
3,401 posts
 
Ralph,
I find the paring of the Contrasts with the ST-70 to be quite adequate in my 12'x15' acoustically treated room. Bass has improved with playing time. The Contrast are certainly revealing such that for my tastes best mated to warmish SS or tube amplification. It was their 16 ohm impedance that drew me toward the purchase. 

Regarding the mono mode question: I am asking about your experience using two ST-70s as mono amps. I believe this is strapping.  Based on the owners manual this can be done.  
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